arch/riscv/kernel/stacktrace.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2008 ARM Limited
   4  * Copyright (C) 2014 Regents of the University of California
   5  */
   6
   7 #include <linux/export.h>
   8 #include <linux/kallsyms.h>
   9 #include <linux/sched.h>
  10 #include <linux/sched/debug.h>
  11 #include <linux/sched/task_stack.h>
  12 #include <linux/stacktrace.h>
  13 #include <linux/ftrace.h>
  14
  15 #include <asm/stacktrace.h>
  16
  17 register unsigned long sp_in_global __asm__("sp");
  18
  19 #ifdef CONFIG_FRAME_POINTER
  20
  21 void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
  22                              bool (*fn)(void *, unsigned long), void *arg)
  23 {
  24         unsigned long fp, sp, pc;
  25
  26         if (regs) {
  27                 fp = frame_pointer(regs);
  28                 sp = user_stack_pointer(regs);
  29                 pc = instruction_pointer(regs);
  30         } else if (task == NULL || task == current) {
  31                 fp = (unsigned long)__builtin_frame_address(1);
  32                 sp = (unsigned long)__builtin_frame_address(0);
  33                 pc = (unsigned long)__builtin_return_address(0);
  34         } else {
  35                 /* task blocked in __switch_to */
  36                 fp = task->thread.s[0];
  37                 sp = task->thread.sp;
  38                 pc = task->thread.ra;
  39         }
  40
  41         for (;;) {
  42                 unsigned long low, high;
  43                 struct stackframe *frame;
  44
  45                 if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
  46                         break;
  47
  48                 /* Validate frame pointer */
  49                 low = sp + sizeof(struct stackframe);
  50                 high = ALIGN(sp, THREAD_SIZE);
  51                 if (unlikely(fp < low || fp > high || fp & 0x7))
  52                         break;
  53                 /* Unwind stack frame */
  54                 frame = (struct stackframe *)fp - 1;
  55                 sp = fp;
  56                 if (regs && (regs->epc == pc) && (frame->fp & 0x7)) {
  57                         fp = frame->ra;
  58                         pc = regs->ra;
  59                 } else {
  60                         fp = frame->fp;
  61                         pc = ftrace_graph_ret_addr(current, NULL, frame->ra,
  62                                                    (unsigned long *)(fp - 8));
  63                 }
  64
  65         }
  66 }
  67
  68 #else /* !CONFIG_FRAME_POINTER */
  69
  70 void notrace walk_stackframe(struct task_struct *task,
  71         struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
  72 {
  73         unsigned long sp, pc;
  74         unsigned long *ksp;
  75
  76         if (regs) {
  77                 sp = user_stack_pointer(regs);
  78                 pc = instruction_pointer(regs);
  79         } else if (task == NULL || task == current) {
  80                 sp = sp_in_global;
  81                 pc = (unsigned long)walk_stackframe;
  82         } else {
  83                 /* task blocked in __switch_to */
  84                 sp = task->thread.sp;
  85                 pc = task->thread.ra;
  86         }
  87
  88         if (unlikely(sp & 0x7))
  89                 return;
  90
  91         ksp = (unsigned long *)sp;
  92         while (!kstack_end(ksp)) {
  93                 if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
  94                         break;
  95                 pc = (*ksp++) - 0x4;
  96         }
  97 }
  98
  99 #endif /* CONFIG_FRAME_POINTER */
 100
 101 static bool print_trace_address(void *arg, unsigned long pc)
 102 {
 103         const char *loglvl = arg;
 104
 105         print_ip_sym(loglvl, pc);
 106         return true;
 107 }
 108
 109 noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
 110                     const char *loglvl)
 111 {
 112         walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
 113 }
 114
 115 void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
 116 {
 117         pr_cont("%sCall Trace:\n", loglvl);
 118         dump_backtrace(NULL, task, loglvl);
 119 }
 120
 121 static bool save_wchan(void *arg, unsigned long pc)
 122 {
 123         if (!in_sched_functions(pc)) {
 124                 unsigned long *p = arg;
 125                 *p = pc;
 126                 return false;
 127         }
 128         return true;
 129 }
 130
 131 unsigned long get_wchan(struct task_struct *task)
 132 {
 133         unsigned long pc = 0;
 134
 135         if (likely(task && task != current && !task_is_running(task))) {
 136                 if (!try_get_task_stack(task))
 137                         return 0;
 138                 walk_stackframe(task, NULL, save_wchan, &pc);
 139                 put_task_stack(task);
 140         }
 141         return pc;
 142 }
 143
 144 #ifdef CONFIG_STACKTRACE
 145
 146 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 147                      struct task_struct *task, struct pt_regs *regs)
 148 {
 149         walk_stackframe(task, regs, consume_entry, cookie);
 150 }
 151
 152 #endif /* CONFIG_STACKTRACE */